Apparatus for using hazardous waste to form non hazardous aggregate

Abstract

Hazardous waste is formed into non-hazardous non-leaching aggregate by introducing the material to a rotary kiln where the large solids are at least partially combusted to form a primary aggregate. Gaseous combustion by-products and waste fines from the waste materials are introduced into at least one oxidizer having water-cooled metal walls. Some of the waste fines are melted to form a molten slag-like material that is removed from the apparatus and cooled to form non-hazardous aggregate. The portion of the material in the oxidizer that is not melted, is cooled, neutralized and subjected to a solid gas separation. The solid is reintroduced to the oxidizer with the primary aggregate where they are either melted or entrained within the molten material and become an integral part of the non-hazardous aggregate.

What is claimed is: 
     
       1. An apparatus for converting hazardous waste into non-hazardous, non-leaching aggregate, said apparatus comprising: a rotary kiln having an entry portion;   oxidizing means adjacent the entry portion of said kiln, said oxidizing means comprising a water-cooled, metal-walled vessel;   a source of solid waste material, said solid waste material comprising large solid waste and waste fines;   means for separating said large solid waste from said waste fines;   means for introducing said large solid waste to said entry portion of said rotary kiln;   means for introducing said waste fines to said oxidizing means;   means for inducing combustion in said kiln to convert said large solid waste to solid particulate primary aggregate, clinker, volatile gases and gaseous combustion by-products;   means for separating said clinker from said solid particulate primary aggregate;   means for inducing combustion in said oxidizing means to convert said waste fines, said volatile gases and said gaseous combustion by-products into noncombustible fines, molten slag, and waste gas;   means for passing said gaseous combustion by-products from said kiln and said waste gas from said oxidizing means;   means for cooling said noncombustible fines and said waste gas;   means for separating said noncombustible fines and said waste gas;   means for introducing said solid particulate primary aggregate and said noncombustible fines, to said molten slag to form a substantially molten mixture;   means for removing said mixture from said apparatus; and   means for cooling said substantially molten mixture to form said non-hazardous, non-leaching aggregate.   
     
     
       2. The apparatus of claim 1 wherein said oxidizing means comprise a plurality of vessels in flow communication with the entry portion of said rotary kiln, said oxidizing means including first and second oxidizers. 
     
     
       3. The apparatus of claim 2 wherein said oxidizing means includes a first oxidizer disposed to receive said waste fines, volatile gases and gaseous combustion by-products from said kiln. 
     
     
       4. The apparatus of claim 2 wherein said oxidizing means includes a second oxidizer disposed to receive said waste fines, volatile gases and gaseous combustion by-products from said first oxidizer. 
     
     
       5. The apparatus of claim 2 wherein said apparatus includes a slag removing vessel in flow communication with said first oxidizer. 
     
     
       6. The apparatus of claim 5 wherein said slag removing vessel includes means for removing said molten mixture from said oxidizing means. 
     
     
       7. The apparatus of claim 6 wherein said slag removing vessel includes a burner for heating material therein. 
     
     
       8. The apparatus of claim 2 wherein said oxidizing means includes a third oxidizer disposed to receive said waste fines, volatile gases and gaseous combustion by-products from said second oxidizer. 
     
     
       9. The apparatus of claim 8 including a cross-over means for connecting said second and third oxidizers. 
     
     
       10. The apparatus of claim 9 wherein said cross-over means comprises a water-cooled, metal-walled vessel connecting said second and third oxidizers. 
     
     
       11. The apparatus of claim 1 including means for introducing said noncombustible particulate fines and said primary aggregate into said oxidizing means. 
     
     
       12. The apparatus of claim 2 including means for introducing said noncombustible particulate fines and said primary aggregate into said second oxidizer. 
     
     
       13. The apparatus of claim 12 including means for removing said molten mixture from said first oxidizer. 
     
     
       14. The apparatus of claim 1 wherein said means for passing said gaseous combustion by-products from said kiln and said waste gas from said oxidizing means includes means for inducing sub-atmospheric pressure in said apparatus. 
     
     
       15. The apparatus of claim 1 wherein said means for separating said large solid waste from said waste fines comprise said rotary kiln. 
     
     
       16. The apparatus of claim 1 wherein the major portion of the vertical walls of said oxidizing means are comprised of substantially vertically oriented tubular conduits. 
     
     
       17. The apparatus of claim 16 wherein the vertical walls of at least one of said oxidizers are comprised of a plurality of parallel metal conduits having a rectangular cross section. 
     
     
       18. An apparatus for converting hazardous waste into non-hazardous, non-leaching aggregate, said apparatus comprising: a rotary kiln having an entry portion;   oxidizing means in flow communication with said kiln, said oxidizing means comprising at least one water-cooled, metal-walled vessel;   a source of solid waste material, said solid waste material comprising large solid waste and waste fines;   means for separating said large solid waste from said waste fines;   means for introducing said large solid waste to said entry portion of said rotary kiln;   means for introducing said waste fines to said oxidizing means;   means for inducing combustion in said kiln to convert said large solid waste to solid particulate primary aggregate, clinker, volatile gases and gaseous combustion by-products;   means for inducing combustion in said oxidizing means to convert said waste fines, said volatile gases and said gaseous combustion by-products into noncombustible fines, molten slag, and waste gas;   means for introducing said solid particulate primary aggregate and said noncombustible fines to said oxidizing means and to said molten slag to form a substantially molten mixture; and   means for removing said mixture from said apparatus.   
     
     
       19. The apparatus of claim 18 wherein said oxidizing means comprise a plurality of vessels in flow communication with the entry portion of said rotary kiln. 
     
     
       20. The apparatus of claim 19 wherein said oxidizing means includes a first oxidizer disposed to receive said waste fines, volatile gases and gaseous combustion by products from said kiln. 
     
     
       21. The apparatus of claim 19 wherein said oxidizing means includes a second oxidizer disposed to receive said waste fines, volatile gases and gaseous combustion by-products from said first oxidizer. 
     
     
       22. The apparatus of claim 18 wherein the major portion of the vertical walls of said oxidizing means are comprised of substantially vertically oriented tubular conduits. 
     
     
       23. The apparatus of claim 18 wherein the vertical walls of at least one of said oxidizers are comprised of a plurality of parallel metal conduits, having a rectangular cross-section. 
     
     
       24. The apparatus of claim 19 wherein said oxidizing means includes a first oxidizer disposed to receive said waste fines, volatile gases and gaseous combustion by-products from said kiln and wherein said oxidizing means includes a second oxidizer disposed to receive said waste fines, volatile gases and gaseous combustion by-products from said first oxidizer. 
     
     
       25. The apparatus of claim 24 wherein said second and third oxidizers comprise two generally cylindrical, vertically-oriented vessels, the upper ends of said vessels having openings therein. 
     
     
       26. The apparatus of claim 25 wherein said oxidizing means includes a cross-over connecting said second and third oxidizers, said cross-over being comprised of a generally U-shaped vessel connecting the top openings of said second and third oxidizers. 
     
     
       27. The apparatus of claim 26 wherein said cross-over comprises a metal-walled, water-cooled vessel. 
     
     
       28. An apparatus for converting hazardous waste into non-hazardous, non-leaching aggregate, said apparatus comprising: a rotary kiln having an entry portion;   oxidizing means in flow communication with said kiln, said oxidizing means comprising at least one water-cooled, metal-walled vessel;   means for controlling the temperature within said oxidizing means;   a source of solid waste material, said solid waste material comprising large solid waste and waste fines;   means for separating said large solid waste from said waste fines;   means for introducing said large solid waste to said entry portion of said rotary kiln;   means for introducing said waste fines to said oxidizing means;   means for inducing combustion in said kiln to convert said large solid waste to solid particulate primary aggregate, clinker, volatile gases and gaseous combustion by-products;   means for inducing combustion in said oxidizing means to convert said waste fines, said volatile gases and said gaseous combustion by-products into noncombustible fines, molten slag, and waste gas;   means for introducing said solid particulate primary aggregate and said noncombustible fines to said oxidizing means and to said molten slag to form a substantially molten mixture;   means for removing said mixture from said apparatus; and   means for cooling said substantially molten mixture to form said non-hazardous, non-leaching aggregate.   
     
     
       29. The apparatus of claim 28 wherein the temperature controlling means includes means for cooling the walls of said oxidizing means.